If you forget your PIN for Seed Vault you’ll need to reset it.
You can recover access as long as you have your seed phrase.
Steps to reset your PIN:
Open System Settings
Select Seed Vault (first option)
Bottom of the page tap Security and Fingerprint
Tap Change Seed Vault Passcode
When prompted for your current PIN, select Forgot Passcode
Read the on-screen steps – this will wipe your seeds from the vault
Reimport your seeds using your seed phrase and set a new PIN